The present disclosure relates generally to turbomachines, and more particularly, to fixtures and methods for transferring turbine blades to a rotor wheel by using components mounted proximally to, and substantially aligned with, the rotor wheel.
Rotors for turbomachines such as turbines are often machined from large forgings. Rotor wheels cut from the forgings are typically slotted to accept the roots of turbine blades for mounting. As the demand for greater turbine output and more efficient turbine performance continues to increase, larger and more articulated turbine blades are being installed in turbomachines. Latter stage turbine blades are one example in a turbine where blades are exposed to a wide range of flows, loads and strong dynamic forces. Consequently, optimizing the performance of these latter stage turbine blades in order to reduce aerodynamic losses and to improve the thermodynamic performance of the turbine can be a technical challenge.
Dynamic properties that affect the design of these latter stage turbine blades include the active length of the blades, the pitch diameter of the blades and the high operating speed of the blades in both supersonic and subsonic flow regions. Damping and blade fatigue are other properties that have a role in the mechanical design of the blades and their profiles. These mechanical and dynamic response properties of the blades, as well as others, such as aero-thermodynamic properties or material selection, all influence the relationship between performance and profile of the turbine blades. Consequently, the profile of the latter stage turbine blades often includes a complex blade geometry for improving performance while minimizing losses over a wide range of operating conditions.
The application of complex blade geometries to latter stage turbine blades presents certain challenges in assembling these blades on a rotor wheel. For example, adjacent turbine blades on a rotor wheel are typically connected together by cover bands or shroud bands positioned around the periphery of the wheel to confine a working fluid within a well-defined path and to increase the rigidity of the blades. These interlocking shrouds may impede the assembly of blades on the rotor wheel. In addition, inner platforms of these blades may include tied-in edges, which also can impede their assembly on the rotor wheel. In some cases, it may be desirable to install multiple turbine blades in a rotor wheel simultaneously. Due to the size and design of each blade, doing so manually or with conventional tools may be impractical.